Climbing device, in particular for a climbing scaffold

ABSTRACT

A self-climbing device, in particular for a climbing scaffolding, with at least one linear drive which produces a relative motion between at least one moving console and at least one mounting rail running in the displacement direction, in particular when the linear drive alternately displaces a scaffolding section and, following attachment of same to the wall and loosening of the attachment of the mounting rail, the mounting rail by a working section, is characterized in that the connection between the linear drive (13) and the mounting rail (6) is established by climbing heads (14, 15) arranged at separations from each other which exhibit at least one pivotable locking member (24) functioning in the manner of a detent pawl and locking cams (29) are provided for on the mounting rail (6) along the path of the locking member (24) during relative motion between the mounting rail and the climbing head which cooperate with same and the locking member (24) is lifted over the locking cams (29) by relative motion in one direction while, in the other direction of motion, abutting the locking cam (29) so that one climbing head form-fittingly connects to the mounting rail (6) to block this relative motion, whereas, on the other climbing head, a relative motion which overcomes the locking cams takes place. The drive is simple and safe.

BACKGROUND OF THE INVENTION

The invention concerns a self-climbing device having at least one lineardrive which produces a relative motion between at least one movingconsole and at least one mounting rail running in the direction ofdisplacement, whereby the connection between the linear drive and themounting rail is effected by means of climbing heads arranged atseparations from each other which exhibit at least one pivotable lockingmember, and with locking cams on the mounting rail in the path of thelocking member during relative motion between the mounting rail and theclimbing head which cooperate with the locking member, whereby thelocking member is lifted during relative motion in one direction overthe locking cams and, in the other motional direction, abuts on thelocking cams so that one climbing head is form-fittingly connected tothe mounting rail to block this relative motion whereas, on the otherclimbing head, a relative motion overcoming the locking cams takesplace.

The scaffold section, during climbing, has no direct connection to theground and no crane is necessary if a linear drive, for example ahydraulic drive, is provided for on the scaffolding which, in a workingstep, lifts the scaffold section on the mounting rails, and in anotherworking step, lifts the mounting rails relative to the scaffoldingsection.

In self-climbing devices which are known in the art as, for example,described in U.S. Pat. No. 4,147,483, the connection between the lineardrive and the mounting rail is effected by pivotable pawls arranged atseparations from each other which exhibit two separated support teeth.The support teeth are lifted over the locking cam during relative motionbetween the pawl and the mounting rail in one motional direction,whereas they abut on the locking cams in the other motional direction sothat the one pawl is form-fittingly connected in a locking fashion tothe mounting rail following this relative motion whereas the other pawlcarries out a relative motion which overcomes the locking cam.

With this type of relative motion the pawl can improperly jam or may notpass by the locking cam in the desired manner. This leads to a jammingof the individual construction elements or in fact to the lack ofengagement of the pawl at the locking cam so that the climbing device isnot sufficiently safe.

It is the underlying purpose of the invention to simplify and rendermore secure the drive mechanism in this type of self-climbing device.

SUMMARY OF THE INVENTION

This purpose is achieved in accordance with the invention in that theclimbing heads exhibit a pivotable control member and a pivotablelocking member and a control curve is provided for on the mounting railin the path of the control member during relative motion between themounting rail and the climbing head and the control member and thelocking member are coupled to each other in such a fashion that thelocking member is rotated by the control curve via the control member inthe other motional direction in such a fashion that the locking memberabuts on the locking cam.

The device in accordance with the invention has the advantage that itfunctions without electronic or electrical components and switches whichcould cause failures and in particular, a locking member drive isprovided for which is adapted to the requirements and loads and which isnot susceptible to breakdown to thereby guarantee as large a degree ofsafety as possible.

Since, the locking member via the coupling is lifted during relativemotion in one direction over the locking cams by the control curve whileabutting in the other motional direction on the locking cam, the lockingmember is form-fittingly held in engagement so that no spring isnecessary therefor which could likewise cause failures.

The invention is suitable, for example, for a self-climbing device withwhich the rails extend over the entire height of the complete motion,for example for elevators or the like. On the other hand if the deviceis to be utilized for a climbing scaffold with which mounting rails andscaffold portions are alternately raised, the height of the mountingrail assumes a value somewhat larger than twice the height of a workingsection, whereby the device in accordance with the invention iscompletely functional not only in one direction of motion but also inthe opposite direction of motion. In an embodiment of the invention theclimbing heads thereby exhibit effective locking members in two opposingmotional directions.

The embodiment in accordance with the invention can also be furtherconfigured such that the control member and the locking member can becoupled to each other in at least two different angular positions,whereby the one angular position is correlated to the lifting of amoving console and the other angular position to the lifting of themounting rail.

In this fashion one guarantees that, for each relative motion, thelocking member engages into the path of the locking cams where it isform-fittingly held by means of the engaging motion which is transferredby the control curve via the control member to the locking member. Inthis fashion, the moving console can, for example, not only besectionswise raised on the mounting rails, but also be sectionwiselowered in the same fashion.

The coupling between the locking member and the control member can beconfigured in an arbitrary fashion.

In an embodiment of the invention the locking member and the controlmember are arranged in a rotatable fashion on a common axis. Thisfacilitates a particularly simple coupling between these two members,for example by means of holes through both members, which are flush inone coupling as well as in another coupling position and through which abolt can be inserted so that the coupling functions integrally.

In an embodiment of the invention the locking member and the controlmember are configured as plates and arranged next to each other.

This embodiment of the invention can be further configured in such afashion that one of the two members exhibits a circular segment shapededge and the coupling exhibits a bolt attached to one of the two memberswhich is movable in a radial direction and which cooperates with catchesarranged on the edge of the other member.

The control member and the control curve can be configured in aplurality of fashions, and it is only important that the control memberand the control curve transfer in a form-fitting fashion a precisemotion from the control curve to the locking member.

In an embodiment of the invention the locking member exhibits two armsextending radially with respect to the pivot axis with, in one couplingposition, the one arm and, in the other coupling position, the other armprojecting into the path of the locking cams.

In an embodiment of the invention the control member also exhibits twoarms extending radially with respect to the pivot axis one of whichcooperates with the control curve.

The control curve can be configured in an arbitrary fashion, for examplefrom a continuous curve line. However, in one embodiment of theinvention, the control curve exhibits individual curve sections whichare arranged distributed along the length of the mounting rail and whichexhibit a section running parallel to the direction of motion at theposition corresponding to the point of deepest engagement of the lockingmember into the path of the locking cams.

This embodiment can be further improved such that the length of thissection of the curved pieces running parallel to the direction of motioncorresponds approximately to the separation between the points withwhich the arms of the control member lie at an angular position on acurve section so that, in one angular position both arms of the controlmember lie on this straight section.

The climbing head in accordance with the invention can also be utilizedwith scaffolds with which one section of a scaffold contains the workingplatform raised by means of a self-climbing device arranged at itsmiddle as well as with scaffolds with which the movable scaffoldingsection is raised by two or more climbing devices which functionsynchronously. The climbing heads can also be provided in other liftingdevices, for example in freight elevators with which the mounting railextends not only along two working positions arranged above anotherrather along the complete height to be travelled by a moving console,for example, for freight elevators in multipil-story warehouses. Theclimbing heads in accordance with the invention can also be provided forwith diagonally running elevators or the like where a compulsory controlby means of a control curve with alternatingly engaging locking memberis advantageous in a lifting device.

Further features of the invention result from the following descriptionof embodiments of the invention in combination with the claims and thedrawing. The individual features can be used individually orcollectively in embodiments of the invention.

An embodiment of the invention is represented in the drawing.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 shows a view of a climbing scaffold,

FIG. 2 shows a section of FIG. 1 in enlarged scale,

FIG. 3 shows a cross-section of an embodiment of a climbing head in moregreatly enlarged scale,

FIG. 4 shows a cut through a lower and

FIG. 5. shows a cut through an upper climbing head.

DETAILED DESCRIPTION

In the embodiment shown in the drawing a plurality of anchoring boltsare imbedded in the poured concrete section of a building wall 1.Scaffolding shoes 4 and 5 are attached to the anchoring bolts 2 and 3which, in turn, are arranged above each other at a separationcorresponding to the height of a concrete section and a mounting rail 6is guided in the scaffold shoes whose height is adjustable, the mountingrails exhibiting an I-shaped cross-section. The scaffold shoe 4 onlyguides the rail 6, whereby the scaffold shoe 5 also exhibits attachmentdevices with which the climbing scaffold, designated in its totality as7, can be attached to wall 1. The climbing scaffold 7 exhibits a workingplatform 8 which has a moving console 9 on the end facing the wall inwhich the mounting rail 6 is guided and which can be suspended andsecured in the attachment device of the scaffold shoe 5. One or moremold elements 10 having the height of a single story are guided at rightangles to the wall 1 on the working platform 8 in a displaceablefashion.

FIG. 1 shows the mold element 10 in a position in which the nextconcrete section can be poured (the usual reenforcement is not shown). Aleading platform 11 is shown in the climbing scaffold above the workingplatform 8 and below the working platform 8 is a trailing platform 12.In the embodiment shown, the climbing of the climbing scaffold 9 intothe next concrete section transpires in a plurality of steps, since alinear drive 13 provided for the lifting of the climbing scaffold 7 isrealized in the embodiment shown by means of a hydraulic cylinder whosestroke is substantially smaller than the height of a story. A spindledrive, chain or a belt drives, rack drives or other devices can,however, be provided for as linear drives which facilitate asubstantially larger stroke, by way of example a stroke which lifts theclimbing scaffold 7 by the full height of a concrete section, forexample, by the height of a single story in a single working step.

A climbing head 14 is located on the lower end of the hydraulic drive 13on its piston rod 16, which cooperates with the mounting rail 6. Aclimbing head 15 is located on the upper end of the hydraulic drive 13which likewise cooperates with the mounting rail 6 and to which themoving console 9 is also attached.

As soon, in the position represented in FIG. 1, as the section of theconcrete wall adjacent to the mold element 10 is poured and completed,the mold element 10 is removed after the concrete has set. Anchoringbolts 17 have already been imbedded in this freshly poured concretesection which can serve for attachment of the scaffold shoes.

The climbing heads 14 and 15 are more precisely described in FIGS. 3-5.The climbing head exhibits a housing 18 which surroundingly engages oneleg 19 of the I-profile of the mounting rail 6. Locking cams 21, 29 arearranged in the longitudinal mid-plane of the rail 6 at separations fromanother on the front surface 20 of the I-profile facing away from thewall 1, whose side surfaces pointing in the direction of motion extendat right angles to the front surface 20. A locking member 24 is locatedin the path of these locking cams 21, 29 which is pivotably supportedabout a bolt 25 in the housing 18 and which exhibits two radial arms 26and 27 each of which seats, depending on the rotational position of thelocking member 24 on the bolt 25 during relative motion between themounting rail 6 and the climbing head 14, on the front surface 22 of theupper locking cam 21 or, as shown in FIG. 2 when moving the upperclimbing head in the upward direction, on the front surface 28 of thenext lower locking cam 29.

Curved members 30 are located at separations from another along thelength of the mounting rail 6 at a separation sidewardly adjacent to thelocking cams 21 and 28 whose side surfaces pointing in the direction ofrelative motion exhibit rise curves 31 and 32. The surfaces 33 facingaway from the mounting rail 6 run parallel to front surface 20. Thecurve members 30 and the locking cams 21, 29 are arranged on themounting rail displaced at heights relative to each other.

The climbing head 14 exhibits a control member 34 which is pivotablysupported about the bolt 25 in the path of this curve member 30, whichlikewise exhibits two radially extended arms 35 and 36. In a middleposition, as shown in FIGS. 2 and 3, the two arms 35 and 36 slide overthe surface 33. The surface 33 is sufficiently long that both arms 35and 36 can simultaneously seat on the surface 33.

The locking member 24 and the control member 34 are plate-shaped and aresupported in a rotatable fashion adjacent to and independent of eachother on the bolt 25. A coupling bolt 38 is mounted in a longitudinallydisplaceable fashion on a part of the control member 34 facing away fromthe mounting rail 6 in an extension 37 whose inner end 39 facing thelocking member 24 cooperates with catches 40 which are carved out of theperiphery of the locking member 24. The end 39 of the coupling bolt 38is pressed against the edge of the locking member 24 by means of apressure spring which is not shown. Fork ends 42 and 44 engaging at bolt25 are part of an attachment component with which the piston rod 16 isattached to the lower climbing head 14 or with which the moving console9 of the working platform 8 or the hydraulic cylinder attached theretois attached to the upper climbing head 15.

The upper climbing head 15 (FIG. 5) is distinguished from the lowerclimbing head 14 only in that the bolt 25 in the climbing head 14 issolely supported in the two outer side housing walls 41 whereas in theupper climbing head 15, two additional intermediate housing walls 43 areprovided for between the outer housing walls 41 and the locking member24 which additionally direct the scaffolding load transferred to themoving console 9 onto the locking member 24 and the mounting rails 6 orthe scaffold shoes 5.

A catch bolt 46 is mounted in the housing 18 in a longitudinallydisplaceable fashion. It exhibits, at its front end, a spring loadedball which snappingly engages depressions on the edge of the lockingmember 24 to hold the control member and locking member, which arerigidly connected to each other by means of the coupling bolt 38, with alow amount of force in a particular rotational position assumed by thesemembers, for example, when travelling over a locking cam 29 and a curvedmember 30.

In the event that the climbing scaffold is to be lifted out of theposition shown in FIG. 1, the attachment of the transport rails 6 in thescaffold shoes 4 and 5 is initially released, whereby the moving console9 connected to the working platform 8 remains secured in the scaffoldshoe 5. If the hydraulic cylinder 13 is then activated, the climbinghead 14 which is attached at the lower end of the piston rod 16 andwhich engages the mounting rail 6 is upwardly displaced together withsame to such an extent as allowed by the stroke of the hydrauliccylinder 13. The mounting rail 6 thereby slides through the climbinghead 15 which allows this motion of the mounting rail 6, whereas the arm26 of the locking member 24 engages into the lower climbing head 14behind a locking cam to thereby urge the mounting rail upward. Themounting rails 6 are then once more secured in the scaffold shoes 4 and5 and the piston rod 16 is activated once more whereby the arm 26 of thelocking member 24 passes over locking cams 21 located along its path andagain engages beneath a locking cam in the lower end position of thepiston rod 16. The mounting rail 6 is thereby again released from thewall and once more raised by a stroke length during the next pulling-inof the piston rod 16 into the hydraulic cylinder 13. This process isrepeated until the mounting rail 16 has been raised by one concretesection to thereby be attached in additional attachment componentsupwardly arranged in the wall. With a 3 m high concrete section and astroke of the hydraulic cylinder of 60 cm this processing stage isrepeated 5 times to lift the mounting rail. Then, in the representationchoosen in FIG. 1, the mounting rail 6 seats with its lower end in thevicinity of the scaffold shoe 4 and projects with its upper endsufficiently far in the upper direction above the scaffold shoe 5 thatthe climbing scaffold 7 can be displaced by one concrete section alongthe support rails 6 attached to the wall.

The climbing heads 14 and 15 are then switched over so that the climbinghead 14 is supported on one of the locking cams 21, 29 of the thensecured mounting rail 6. The attachment of the moving console 9 in thescaffold shoe 5 is then released and the hydraulic cylinder 13 is drivenout whereby the upper climbing head 15 which then slides along themounting rail 6 in the upper direction, urges the moving console 9 andthereby the hydraulic cylinder 13 in the upper direction. When thepiston rod 16 is in the outward position, the moving console 9 andthereby the climbing scaffold 7 are attached to the wall and the pistonrod 16 is again introduced into the cylinder 13 whereby the arm 27 ofthe locking member 24 engaging, after the switching over of the climbingheads, into the mounting rail 16 and thereby into the path of thelocking cams 21, 29, glides over the locking cams 21, 29 due to itssmooth lower surface 45.

In the event that the piston rod 16 is completely driven-in, theattachment of the moving console 9 is once more released whereby thescaffold is supported in the climbing heads 14 and 15 by means of thearms 27 of the locking member 24 supported at the locking cams. Thepiston rod 16 is then driven-out once more and the moving console 9, thescaffolding and the hydraulic cylinder 13 are thereby driven upwardly byone stroke length, whereby the arm 27 of the locking member 24 of theupper climbing head 15 engaging into the path of the locking cams 21, 29slides over the locking cams with the flat lower surface 45 of thelocking member 24.

This process is continued until the working platform 8 has been liftedby one concrete section after which, following reenforcement work andother preparatory work, the molding element 10 is once more positionedinto the molding plane and attached there so that concrete can be pouredin this section.

Individual working steps are described more closely below.

In the position of the locking member 24 and control member 25represented in FIG. 2, which is determined by the engagement of thecoupling bolt 38 into the uppermost catch 40 in FIG. 5 of the lockingmember 24, the arm 35 of the control member 34 still lies on the uppersurface 33 of the curved member 30 and the arm 27 of the locking member24 is urged by the arm 35 to be adjacent to the front surface 20 of theleg 19 of the mounting rail 6. In this position the mounting rail 6 issecured in the scaffold shoes 4 and 5, whereas the attachment of themoving console 9 at the scaffold shoe 5 is released so that the movingconsole 9 can be displaced along the mounting rails 6. In thisrepresentation according to FIG. 2 one assumes that the mounting rail 6has already been transported upwardly in a preceding working step abovethe position shown in FIG. 1. If the hydraulic cylinder 13 is thanactivated, the climbing head 14 moves by a small amount downwardly fromthe position represented in FIGS. 2 and 5 until the arm 27 of thelocking member 24 seats on the upper outer surface 23 of the locking cam29 to thereby support the lower climbing head 14. Subsequently, due tothe fact that the mounting rail 6 is rigidly connected to the wall, thehydraulic cylinder 13 moves upwardly in the direction of the arrow 44,whereby it displaces the upper climbing head 15 and the moving consoleconnected thereto along the mounting rail 6 in the upward direction. Theposition of the locking member 24 and the control member 34 is the samein climbing head 15 as in climbing head 14 since, also for climbing head15, the coupling bolt 38 engages into the same catch 40 of the lockingmember 24. Although, during this upward motion, the flat lower surface45 of the locking member 24 seats diagonally on the next higher lockingcam, the upper climbing head 15 can nevertheless travel over thislocking cam since, as one can see in FIG. 2 with respect to the lockingcam 21, the locking member 24 is somewhat rotated in a counterclockwisedirection until the arm 27 can slide over the upper surface of thelocking cam 21. The control member 34 does not cause interference duringthis rotating motion since its arm 35 has already left the relevantcurve member 30 due to the vertical displacement between the locking camand the curve member so that the control member 34 can exercise thisrotating motion. During this lifting of the scaffolding 7 same issupported on the lower climbing head 14 and, via the arm 27 adjacent tothe locking cam 29, on the mounting rail 6 which, as mentioned, issecured during this motion in the scaffold shoes 4 and 5 and thereby inthe wall 1.

When this motion is completed the moving console 9 is suspended andsecured at the next higher scaffold shoe. The piston rod 16 is thenmoved-into the hydraulic cylinder 13 with same raised by the climbinghead via the preceding working step. In this return stroke the lowerclimbing head 14 passes over the locking cams in the same manner as hadpreviously the upper climbing head 15. The moving console is then againreleased from the wall 1 so that, when driving out the piston rod themoving console, supported on the lower climbing head 14 is again raisedby a stroke length. When the scaffolding has reached its upper endposition following a plurality of working steps and is attached to thewall, the locking member 24 is rotated relative to the control plate 35by loosening of the coupling bolt 38 in such a manner that the couplingbolt 38 then engages into the lowermost catch 40 of the locking member24 in FIG. 5. In this fashion, in the position represented in FIG. 3,the arm 36 of the control member 34 is moved downwardly in acounterclockwise direction so that same, when abutting on the risesurface 31 of the next curve member 30, pivots the mutually coupledplates of the locking member 24 and locking member 34 in acounterclockwise direction so that the arm 26 is guided on the frontsurface 20 of the mounting rail 6 and, when further lifting the lowerclimbing head 14, seats on the front surface 22 of the locking cam and,by further raising of the climbing head 14, carries the mounting rail 6upwardly. The upper end of the hydraulic cylinder 13 is thereby abovethe upper climbing head 15 and the moving console 9 is rigidly connectedto the wall.

When the piston rod 16 is driven-in the mounting rails 6 are, in thisnew position, once more secured in corresponding scaffold shoes and thepiston rod 16 is driven-out in a return stroke (e.g. without load). Theabove mentioned process for lifting the mounting rails is then repeated.

In the event that the scaffolding is to be lifted again, the couplingsin the climbing heads are once more released and locking member 24 andcontrol member 24 are pivoted with respect to each other in such afashion that the coupling bolt 38 once more engages into the uppermostcatch 40 of FIG. 3 so that both members again assume the positionrelative to each other shown in FIG. 3. The moving console 9 is thenreleased from the scaffold shoe in which it had been attached and a newworking sequence is introduced by activating a cylinder 13 with whichthe lower climbing head once more is supported on the mounting railwhich is now attached to the wall to upwardly displace the upperclimbing head 15 together with the scaffolding 7.

When the mounting rail 6 and then the scaffolding 7 are to be lowered,the coupling in the climbing heads, with climbing head 15 attached tothe wall, is adjusted in such a fashion that the coupling bolt 38engages into the lowermost catch to thereby pivot the arm 26 of thelocking member 24 in a counterclockwise direction so that same engagesat a lower outer surface 22 as soon as the mounting rail 6 is releasedfrom its scaffold shoe for downward motion. The mounting rail 6 thenmoves, when positioning-out the piston rod 16, along with the lowerclimbing head 14 in a downward direction. The mounting rail 6 is, forits part, then attached to the wall and, following a return stroke, thisworking step is repeated. If the mounting rail 6 is in its lower endposition, the coupling in the climbing heads is switched over again, theupper climbing head 15 is released from the wall, and the piston rod 16is driven-in once more, whereby the scaffolding 7 connected to the upperclimbing head 15 is lowered by the stroke of the hydraulic cylinder 13.

Clearly, following the first lifting step one can also attach the movingconsole 9 to an anchoring bolt in the wall. However, it would then benecessary, with a stroke of 60 cm, to provide an anchoring bolt in thewall at intervals of 60 centimeters, something which is avoided when,during these intermediate steps, the moving console 9 is only attachedto the mounting rail 6. Anchoring bolts are thereby only required atseparations corresponding to the height of a story in the scaffoldingshoes of which the climbing scaffolding 7 is suspended in its raisedfinal position and to which the transport rail 6 is attached when sameis guided into the raised position which, in the current example,likewise transpires in individual steps of the size of the stroke of thehydraulic cylinder 13.

If a plurality of such raising mechanisms are engaged on a singlescaffolding section, the hydraulic cylinders 13 are connected to eachother by an apparatus known in the art which guarantees a precisesimultaneous travel of the hydraulic cylinders 13.

Clearly, the invention can also be realized in embodiments with which alinear drive is utilized whose stroke is as large as a concrete section.The steps between switching over of the couplings in the climbing headsare thereby eliminated.

I claim:
 1. A self-climbing device comprising:a moving console; amounting rail extending in a direction of displacement; a linear devicemeans to produce a relative displacement between the moving console andthe mounting rail; a first and a second climbing head connected betweenthe linear drive means and the mounting rail, the first and the secondclimbing head being separated from each other, each of the first and thesecond climbing heads having a pivotable locking member and a pivotablecontrol member coupled to the pivotable locking member; locking cammeans integral with the mounting rail and cooperating with the lockingmember during relative displacement between the mounting rail and theclimbing head; and a control curve means integral with the mounting railand cooperating with the control member during relative displacementbetween the mounting rail and the climbing head, wherein the controlcurve means rotates the locking member via the control member to abutthe locking member on the locking cam means during relative motion in afirst direction, the locking member being lifted over the locking cammeans during relative motion in a second direction.
 2. The device ofclaim 1, wherein the locking member is adapted to operate in twoopposing displacement directions.
 3. The device of claim 1, wherein thecontrol member and the locking member are adapted for coupling at afirst and a second angular position, the first angular position fordisplacement of the moving console and the second angular position fordisplacement of the mounting rail.
 4. The device of claim 1, wherein thelocking member and the control member are adapted to rotate about acommon axis.
 5. The device of claim 4, wherein the locking member andthe control member each comprises a plate.
 6. The device of claim 4,wherein one of the locking member and the control member has a circularshaped edge section and further comprising spring loaded bolt meansattached to the locking member and cooperating with catches in thecontrol member.
 7. The device of claim 4, wherein one of the lockingmember and the control member has a circular shaped edge section andfurther comprising spring loaded bolt means attached to the controlmember and cooperating with catches in the locking member.
 8. The deviceof claim 3, wherein the locking member comprises a first and a secondarm extending radially from a pivot axis, the first arm projecting intoa path of the locking cam means in the first angular position and thesecond arm projecting into the path of the locking cam means in thesecond angular position.
 9. The device of claim 1, wherein the controlmember comprises a forward and a backward arm extending radially from apivot axis, the forward arm cooperating with the control curve means ina forward displacement direction.
 10. The device of claim 1, wherein thecontrol curve means comprises curve members distributed along themounting rail, the curve members having an edge facing away from themounting rail and extending parallel to the direction of displacement.11. The device of claim 10, wherein the control member comprises aforward and a backward arm and the edge has a length corresponding to aseparation between points at which the forward and backward arm lie on acurve member.
 12. The device of claim 1, wherein the first and thesecond climbing heads each comprise a coupling bolt for coupling thelocking member to the control member, a housing, and a catch bolt guidedin a longitudinal displaceable fashion in the housing and adapted tohold the locking member and the control member at an angular positionwhen passing over one of the locking cam and the control curve means.